Amylosic material plasticized with quaternary ammonium salt



United States Patent 3,314,810 AMYLOSIC MATERIAL PLASTICIZED WITH QUATERNARY AMMONIUM SALT Austin H. Young, Decatur, Ill., assignor to A. E. Staley Manufacturing Company, Decatur, Ill., a corporation of Delaware No Drawing. Filed June 19, 1963, Ser. No. 288,897 20 Claims. (Cl. 106-210) This invention relates to amylose plasticized with water-soluble quaternary ammonium salts.

For years amylose films have been studied from a more or less academic point of view since amylose was not commercially available. Now that amylose has be come available in sizeable quantities research on amylose films has increased. One of the major problems, which has slowed the commercialization of amylose films, is that the flexibility and elongation of amylose films is dependent upon the water content of the amylose film. At low relative humidity, water is lost by evaporation, and the film becomes extremely brittle and its percent elongation decreases. Even at 50% relative humidity the film has a low percent elongation and poor flexibility. Until now no adequate plasticizer or combination of plasticizers has been found for amylose.

Various attempts to find plasticizers for amylose have centered upon humectants, which would retain water at low relative humidity. Glycerol has generally been considered the best amylose plasticizer. However, glycerol is sadly deficient. At low relative humidity, glycerolplasticized amylose films have about the same elastic modulus and percent elongation as unplasticizecl amylose films. At about 50% relative humidity, the glycerolplasticized amylose films have an inital percent elongation and elastic modulus that are markedly better than those of unplasticized amylose. However, the improvements imparted by humectants such as glycerol are only temporary. On aging the elastic modulus of amylose films plasticized with glycerol increases and percent elongation decreases to the point where the plasticized film is not appreciably different from the unplasticized film.

The object of this invention is to provide improved plasticizers for amylose films.

I have now found that water-soluble quaternary ammonium salts are excellent amylose plasticizers, whose plasticizing effect is independent of the age of the amylose film. These plasticizers are effective in reducing the elastic modulus of amylose films at low relative humidity. The water-soluble quaternary ammonium salts, which contains at least one hydroxyalkyl group (preferably the hydroxyethyl group) are preferred since they are extremely effective in increasing the percent elongation of amylose films at low relative humidity.

These plasticizers can be represented by the formula:

1's wherein R R R R can be methyl, ethyl, propyl, butyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, cyanoethyl, etc., and X is an anion. Suitable plasticizers represented by the above formula include choline chloride, choline bromide, methyl tri (2-hydroxyethyl) ammonium chloride, methyl tri (2hydroxyethyl) ammonium methyl sulfate, dimethyl di (Z-hydroxyethyl) ammonium methyl sulfate, dimethyl di (Z-hydroxyethyl) ammonium chloride, triethyl 2-hydroxypropyl ammonium chloride, triethyl 2- cyanoethyl ammonium chloride, tetramethyl ammonium chloride, tetraethyl ammonium chloride, tetrabutyl ammonium chloride, etc.

a total of from 4 to 16 carbon atoms.

All of these plasticizers contain 3,314,810 Patented Apr. 18, 1967 The weight ratio of amylose plasticizer to amylose (dry solids basis) can range from about 5:95 to 60:40 when the quaternary ammonium salt is the sole plasticizer. Under most conditions the quaternary ammonium salt is preferably used in a concentration of from about 10 to 40 parts by weight with correspondingly to 60 parts by weight amylose.

For the purpose of this invention, the term amylose refers to the amylose resulting from the separation of the amylose and amylopectin components of starch, or the whole starch which is composed of at least50% amylose. Commercially available sources of amylose include Nepol amylose (the amylose fraction of corn starch), Superlose (the amylose fraction of potato starch), Amylomaize or Amylon (high-amylose corn starch containing approximately 54% amylose), Amylon VII (high-amylose corn starch containing up to 70% amylose), etc. The amylose films based on high-amylose corn starch can be simulated by mixing corresponding concentrations of separated amylose with separated amylopectin. Preferably, the amylopectin content of the amylose is less than 20% by weight. In general, the higher the concentration of amylose the better the tensile strength of the film. Various derivatives of amylose (amylose acetate, hydroxyethyl amylose) such as those described in British specification 871,634, published June 28, 1961 can also be employed.

The amylose films can be prepared by any of the prior art techniques, such as those described in any of US. Patents 2,608,723 to Wolff et al., 2,903,336 to Heimstra et. al., 2,973,243 to Kudera, 3,030,667 toKunz, etc. In these processes the amylose plasticizer (in either the dry form or dissolved in water) is added to a suitable aqueous solution of amylose (in aqueous alkali, aqueous formaldehyde, in hot water at pH 7, etc.). The amylose solution is then cast on a suitable substrate, such as a moving belt, or extruded into a coagulating (acidic or salt) bath. In this way the amylose film is recovered from the aqueous solution by the precipitation of the amylose film from the solvent or by evaporating the solvent.

These techniques can be employed to prepare self-supporting films, which are large in two dimensions and small in the third dimension. The previously prepared films can also be laminated to a suitable base or the film can be cast or otherwise applied directly on a suitable substrate, e.g., cellulose (cellophane, paper), metal, etc.

The amylose film can also be prepared by extruding superficially dry amylose and quaternary ammonium salt. This extrusion technique is described in detail in commonly assigned application Ser. No. 244,127, filed Dec. 12, 1962.

The following examples are merely illustrative and are not to be construed as limiting the scope of my invention. All of the data in the examples is an average of five determinations.

Example I An aqueous solution of corn amylose was prepared by passing an aqueous slurry of 8 grams corn amylose (d.s.b.) in 72 grams of water through a 35 foot long coil heated to 150 C. having an inside diameter of A;", an outside diameter Ma" and a dwell time of 2 minutes. The aqueous solution was cooled to C. and placed in a preheated Dewar flask, which contained 2 grams of choline chloride dissolved in 2 grams water (95 C.). The solution was stirred for 60 seconds and then cast on a lecithin-coated glass plate at 30 C. using a doctor blade preheated to 95 C. The film gelled rapidly at room temperature. The same techniquewas employed for pre paring any amylose film having no plasticizer, an amylose film containing 20% by weight glycerol and an amylose film containing 20% by weight tetramethyl ammonium 3 chloride. Each film was stripped from the glass plate and stored at 23 C. and 50% relative humidity. The percent elongation and elastic modulus of the films were determined periodically. The results are set forth below in Table I where E.M. stands for elastic modulus in ployed in a concentration of between to 30 percent by p.s.i. and E stands for percent elongation. weight of the amylose film in order to increase the percent TABLE 1 Thickness Age of Film in Weeks Properties Plastioizer of Film J -4 sted in Mils None 3:333:11: 1:311:33: 9 Glycerol Q9 132, 000 153, 000 223, 000 258,003 Tetramethylammgnium chm L3 It 33,200 54,100 51, 500 mag 11 0. }Ch0une chloride" L1 59,300 108,000 14,900 73,10

The above table illustrates that the plasticizing effect elongation at low humidity. However, chloine chloride of water-soluble quaternary ammonium salts is retained is effective in smaller concentrations. The above data when amylose films are aged. This is in direct contrast also indicates that quaternary ammonium halides are to the plasticizing effect of glycerol, which is normally more effective plasticizers than the comparable quaternary considered the best amylose plasticizer. ammonium methyl sulfates.

Exam le H Since many embodiments of this invention ma p and since many changes may be made in the embodiments A series of 1 mil corn amylose films having varying described, the foregoing is to be interpreted as illustrative concentrations of plasticizers were prepared in the manner only and my invention is defined by the claims appended described in Example 1 and then stored at 23 C. and 50% relative humidity for one week. The results are set forth below in Table II.

The above data illustrates that quaternary ammonium salts having at least one hydroxyalkyl are effective in increasing the percent elongation of amylose films at low humidity. In general, these plasticizers must be emhereafter.

I claim: 1. A continuous amylosic TABLE II Weight Percent Plastieizer in Properties Film Tested Plasticizer 1 }Choline chloride 3g 3g 070 }Tetramethyl ammonium chloride 9g 2g 9g E.M }Mcthyl tri (2-hydroxyethyl) ammonium 216,000 08,000 22,500 chloride. 25 20 22 E.M Methyl tri (Z-hydroxyethyl) ammonium 276,000 94,000 51,000 E methyl sulfate. 24 1s E.M Dimethyl di (2-hydroxyethy1) ammoni- 289,000 123,000 51,500 E 11m methyl sulfate. 11 26 32 EM }Dimethyl di (2-hydroxyethyl) ammoni- {213,000 35,800 10,200 E um chloride. 10 23 22 1 Compound was prepared by quatcrnizing triethanol amine with dimethyl sulfate. 2 Compound was prepared by methylating dicthanol amine with dimethyl sulfate.

Example Ill Example 11 was repeated except that the films were stored at 23 C. and 23% relative humidity for one week. The results are set forth below in Table III.

film comprising an amylosic 55 present in the form of a material containing at least 5 0% by weight amylose wherein the amylose portion of said amylosic material is material selected from the group consisting of the separated amylose fraction of whole TABLE III I Weight Percent Plastieizer in Properties Film Tested Plasticizer %.M 367, 00(8) 221, 000 Not run. }Choline chloride 9g g? 22 g" :1: }Tetramethyl ammonium chloride g g g E. }Methyl tri (2-hydroxyethyl) ammonium 440,000 228,000 59,300 E chloride. 7 20 27 E. lMethyl tri (2-hydroxyethyl) ammonium 445,000 217,000 133,000 J methyl sulfate. 6 23 18 Dnnethyl d1 (Z-hydroxyethyl) ammoni- 491,000 260,000 101,000 um methyl sulfate. 3 14 25 }Dimethyl di (2-hydroxyethyl) ammoni- 409,000 105,000 42,000 um chloride. 5 21 29 starch, whole starch contining at least 50% by weight amylose and mixtures thereof, plasticized with a plasticizing concentration of a water-soluble quaternary ammonium salt having a total of from 4 to 16 carbon atoms.

2. The article of claim 1, wherein the weight ratio of quaternary ammonium salt to amylosic material ranges from 5:95 to 60:40.

3. The article of claim 2, wherein said quaternary ammonuim salt contains at least one hydroxyalkyl group.

4. The article of claim 3, wherein the anion portion of said water-soluble salt is a halide.

5. The article of claim 2, wherein the amylopectin content of said film is less than 20% by weight.

6. The article of claim 2, wherein the amylosic ma terial is the separated fraction of whole starch.

7. The article of claim 2, wherein said quaternary ammonium salt is a choline salt.

8. The article of claim 2, wherein said quaternary ammonium salt is a salt of methyl tri (Z-hydroxyethyl) amine.

9. The article of claim 2, wherein said quaternary ammonium salt is a salt of dimethyl di (Z-hydroxyethyl) amine.

10. The article of claim 2, wherein said quaternary ammonium salt is a salt of tertamethyl amine.

11. A composition comprising an amylosic material containing at least 50% by weight amylose wherein the amylose portion of said amylosic material is present in the form of a material selected from the group consisting of the separated amylose fraction of whole starch, whole starch containing at least 5 0% by weight amylose and mixtures thereof, plasticized with a plasticizing concentration of a water-soluble quaternary ammonium salt having a total of from 4 to 16 carbon atoms.

12. The composition of claim 11, wherein the weight 6 ratio of quaternary ammonium salt to amylosic material ranges from 5 :95 to :40.

13. The composition of claim 11, wherein said quaternary ammonium salt contains at least one hydroxyalkyl group.

14. The composition of claim 13, wherein the anion portion of said water-soluble salt is a halide.

15. The composition of claim 12, wherein the amylopectin content of said film is less than 20% by weight.

16. The composition of claim 12, wherein the amylosic material is the separated fraction of whole starch.

17. The composition of claim 12, wherein said quaternary ammonium salt is a choline salt.

18. The composition of claim 12, wherein said quaternary ammonium salt is a salt of methyl 'tri (2-hydroxyethyl) amine.

19. The composition of claim 12, wherein said quaternary ammonium salt is a salt of dimethyl di (2hydroxyethyl) amine.

20. The composition of claim 12, wherein said quaternary ammonium salt is a salt of tetramethyl amine.

References Cited by the Examiner UNITED STATES PATENTS 2,288,413 6/1942 Morgan 260-5676 2,304,252 12/1942 Hager et al 106-210 XR 2,419,281 4/1947 Noble 1. 106210 2,514,131 7/1950 Kaszuba 106186 2,656,571 10/1953 Davis et al 264-217 2,943,071 6/1960 Laden 106-210 3,024,283 3/1962 Metcalfe et al. 260-567.6 3,117,014 1/1964 Klug 106213 ALEXANDER H. BRODMERKEL, Primary Examiner. L. B. HAYES, Assistant Examiner. 

11. A COMPOSITION COMPRISING AN AMYLOSIC MATERIAL CONTAINING AT LEAST 50% BY WEIGHT AMYLOSE WHEREIN THE AMYLOSE PORTION OF SAID AMYLOSIC MATERIAL IS PRESENT IN THE FORM OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF THE SEPARATED AMYLOSE FRACTION OF WHOLE STARCH, WHOLE STARCH CONTAINING AT LEAST 50% BY WEIGHT AMYLOSE AND MIXTURES THEREOF, PLASTICIZED WITH A PLASTICIZING CONCENTRATION OF A WATER-SOLUBLE QUATERNARY AMMONIUM SALT HAVING A TOTAL OF FROM 4 TO 16 CARBON ATOMS. 